WHAT AM I DOIN' WRONG??

You don't have a starting @LOOP label...

You have to write. CLS PRINT "PRESS A TO START!" @LOOP IF BUTTON()==16 THEN @CO1 GOTO @LOOP @CO1 END

And we can write shorter. CLS:? "PRESS A TO START! WAIT 60 REPEAT:UNTIL BUTTON()==16

CLS:PRINT"PRESS a TO START! REPEAT:UNTIL BUTTON()==#A

Replace this with line 3: A=BUTTON(2) IF A==16 THEN...

if button<==16 <A> then goto @loop